Automatic control for motors



Aug. 1s, 1931.

A. C. DURDIN, JR

AUTOMATIC CONTROL FOR MOTORS Filed Nov. l0. 1928 2 Sheets-Sheet l nfs-flug, i

Aug' 18 1931- A. c. DURDlN, JR 1,819,774

AUTOMATIC CONTROL FOR MOTORS Fi1edNov. 1o. 192.8 2 sheets-sheet 2 Patented Aug. 1s, 1931 UGUSTUSC. DURDIN, JR., OF CHICAGO, ILLINOIS AUTOMATIC 'CONTROL ron morons u Applieaition med November 1o, 192s. serial No. 318,551.

g The invention relates to automatic control for motors, and its principal object is to prolvide automatic pneumatically controlled mechanism for alternately starting electric 5 motors and stopping the active motor after its work has been done, which mechanism is made responsive to changes'of pressure in a tank or other part of a pneumatic system.

. In systems 'usino' air' pressure or vacuum,

1.0 ithas been found tk at the use of two electric motor operated pumps Lfor creating pressure or vacuum is advantageous,`since it avoids.

discontinuance of 'theservice in case one of the pumps becomes disabled, or in case one of "i the 'pumps is unable to supply the necessary pressure or vacuum. `Furthermore, by employing two pumps and causing them to opervate` alternately, the wear and tear on the motors and pumps is lessened. .4 29 With these and other objects and advantages in view, this, invention consists in a' pneumatic. control for motors embodying a vd ouble throw switch, or'other switch mechanism, for two motors, which switch mechaa nism is operated, so as to cause alternate operation of .the motors, by a pneuniatically actuated device connected to the tank or other part of the system in which pressure orvacvuum is to be maintained. It'further consists i in an apparatus of the above described character in; whichthe electric circuit through the double throw or other switch mechanism is opened and closed by a pneumatically operateddevice which is made responsive to the 5t' changes of pressure in the tank or other part of the pneumatic system. It further consists in anapparatus as above described in which the circuit through said A switch mechanism to the idle motor is closed si whenever the pressure in the tank or other p part of the system falls to an abnormally low degree, whereby the idle motor will be started as an auxiliary to the active motor. The in- 1 vention further consists in the several novel features hereinafter fully {set forth and .Y claimed. Y u

- The invention is clearly illustrated in the `drawings accompanying this specification in whichf' f A f 3 Figure 1 is a diagrammatic view illustrating a simple form of the present invention;

Fig. 2 is a front elevation of one form of double throw switch used;

Fig. 3 is a front elevation of said switch with the y movable contact members thereof I55 omitted;

- Fig. 4 is a detail horizontal section taken on the line 4-'-4 of Figs. 2 and 3:

Fig..5 is a detail horizontal section taken on the line 5 5 of Fig. 3; 60

Fig. 6 is a detail horizontal section taken on the line 6'-6 of Fig. 3; and

Fig. 7 is a diagrammatic view illustrating a modified form of the invention.

Referring to said drawings, and first to Figs. 1 to 6 inclusive which illustrate one embodiment of the invention applied to a pressuresystem, the reference character C designates a pressure tank in which it is desired to maintain a predetermined pressure. Twov 7 electric motor driven pump units 1 and 2 are employed for supplying compressed air to the tank C, the pump of the pump unit being connected thereto by a pipe 3 and the pump of the pump unit 2 by a pipe 4. Starters 5 and 6 are provided for the electric motors 7 and 8 of the pump units, and from said starters 5 and 6 run the electric conductors 9 and 10 which are connected to any suitable source of electric supply. 80

For causing the motors to operate'alternately, a double throw switch D, or other switch mechanism for controlling the circuits to two motors, is employed, which switch mechanism is actuated by mechanism made responsive to the variations of lpressure in the tank C, so as to cause the alternate operation of thetwo motors, as will be hereinafter explained. Electric conductors 11 and 12 from the starters 5 and 6 run to the stationary contact members 13 and 14 of the double throw switch D. From the movable contact members 15 of the switch, both circuits are continued through electricconductors `16 to stationary contact members 17 of a switch 18 which is actuated by a pneumatically operated circuit closing device, or pressure switch, here shown in the form of a diaphragm device A connected to the tank C. l,

It is to be understood that as the pressure in the tank rises, the arm a of the diaphragm device Alis moved upwardly against the action of a spring a', and that when the pressure in the tank is sutlicient to overcome the action of the spring a', the diaphragm arm a is raised, thereby breaking the circuit between vthe stationary contac't members 17. Whenever the pressure in the tank falls below a predetermined point, the spring a lowers the arm a and closes the circuit through the stationary contact members 17, thereby closingthecircuit to 011e of the starters 5 and 6, depending upon which circuit is closed through the double throw switch D.

'A second pneumatically operated circuit controlling device or pressure switch, here shown in the form of a diaphragm device B, is connected to the pressure tank C, which diaphragm device is set to operate and thereby close the circuit to the idle pump motor whenever the pressure in the tank C falls below that required to start either pump motor. The diaphragm device B actuates a switch 19 containing stationary Contact members 20 from which lead electric conductors 21 which run to the movable contact members 22 of the double throw switch D, and from the terminals 23 and 24 of said double throw switch B, branch conductor wires 11a andv 12a run to and join witli the electrieconductors 11 and 12. It will be seen, therefore, that if the circuit to thelmotor 7 of the pump unit 1 is closed by the diaphragmA and the pump unit 1 fails to supply the necessary pressure in the tank C, or at least in case the pressure in the tank C continues to Jfall below the pressure at which the pump unit 1 was started,

' then the arm b of the diaphragm device B will be drawn down by the spring, thereby closing the circuit through the stationary contact members. 20 and through the motor 8 of the pump unit 2, and both pump unitsl therefore will continue to operate until the pressure in the tank rises'suiiciently to actuate the diaphragm device B and thereby break the circuit to one of the starters, after which the;A other motor will continue to operate and build up pressure until the vdiaphragm device A is actuated, thereby breaking the circuit to the starter of the active pump.

The double throw switch D is actuated by a switch actuating member F which is actu-V ated by a pneumatic device E, here shown inthe form of a diaphragm device connected y The arm e of the diaphragm device E is connected to the switch operating member F by a link or rod f. A coiled spring f^ is provided for moving the diaphragm device arm e downward against the air pressure exerted on the diaphragm of the diaphragm device E, and said spring is regulated so as to move the arm e down to thereby actuate the switch operating member F before the pressure on the underside of the diaphragm of the diaphragm deinsulated away from each other and from the shaft. The conductors '16 and 21 from the diaphragm devices A and B run to the movable contact members 15 and 22, as has been explained, and by rocking said movable contact members from one side to the other of the switch thereby making contact with the stationary contact members, the circuitto either pump motors 7 or 8 is closed through the switch, depending upon which side of the switch the contact is made. d is rotatably mounted in bearing brackets cl secured upon the frame member d2 of the switch.

The switch operating member Fmay take" any suitable form for actuating the double throw switch. It is here shown as comprising a block f2 slidably guided upon the frame member d2 and having a continuous cam groove f3 in which is held one end of an arm f4 which is rigidly mounted upon the rock shaft d of the double throw switch. The cam groove f3 contains two parallel portions f5 which are joined adjacent the top and bottom thereof by oblique portions f and f. For guiding the end of the arm f* to follow the proper course through the continuous groove f3, oneside wall of which groove is formed by oscillatory blocks f and f8 which are pivotally mounted on the main block f24 and normally held with their side edges out of alignment with the grooves, as is clearly shown in Fig. 3.

The block f7 is frictionally or'otherwise held in any position occupied by it by al spring 79 (see Fig. 5) surrounding the,spin dle flo that forms the pivot upon which the block f7 turns, and bearing against the back plate f in which the spindle is rotatably mounted. The back plate f is rigidly fastened or formed as a part of the body portion of the main block f?. The blocks fs are spring pressed in the direction of the arrows indicated therein in Fig. 3 by springs f12 (see Fig. 6) which surround the spindles fla of the/blocks f8, and have their outer ends secured to thel spindles and their inner ends secured to the back plate fu.

It is to be observed that when the switch operating member F is moved upwardly, the end of the arm f4 tracks inthe upright part f5 of the groove, during which time the movable contact l-members of the double throw switch remain in contact with the stationary The rock shaft i v throw switch D.

contact ymembers on the left hand side of the switch. When the switch operating mem- 'ber F moves downwardly, the end of the arm f* tracks along the oblique portion f of the cam groove to the top thereof, spreading apart the blocks f and f8 and entering the upper end of the other upright groove f5' During the movement of the arm f4 through the oblique portion f of the cam groove, the movablecontact members of the switch' are thrown over to the other side, thereby making contact with the stationary contact members on the right hand side ofthe switchboard. When the switch operating member F is next moved down and up again, the same action upon the arm f4. takes place as has been above described, except that the arm f4 moves up the other inclined portion f of the cam groove and=-is swung to the right as viewed in Fig. 3, and the movablecontact members are 'moved into contact with the stationary contact members at the left of the switchboard. t v

It, is to be observed that the switch is thrown while the pressure in the tank is lowlering, and-consequently, while the motors 'are at rest, and in order to accomplish this, the diaphragm devices are adjusted, so that the circuit through either motor will not be closed by the diaphragm device A until the diaphragm device E has thrown the double In the modilied form of the invention illustrated in Fig. 7 the presspre switches A and B, the pumping units land 2, the double throw switch D, theswitch throwing device F therefor,'land the pneumatically operated device E for actuating the switch throwing device F, are the same as in .the preferred form, and the pressure switches A and B and pneumatic device E are connected to the pressure tank C in the same mannenas in the preferred form. However, the motors of the `pump units are of the type which do not require starters and, consequently, the starters shown .in the preferred form are omitted. The wiring between the switches and motors is substantially-the same as that of the preferred form, except that the service wires 9a run through a switch S and thence toa double 'pole switch 17a which is actuated by the diaphragm device 'of the pressure switch A,

and from said double pole switch 17a, the electric conductors 16a run to the movable contactmembers l5 of the double throw switch l).

A' double. pole switch 19a is provided iny connection with the' diaphragm device of the pressure switch B and. electric conductors 9* run `from the electric conductors 9.' to said double pole lswitch -19, and from thence the electric conductors 21'Il run to the other two movable Contact v members of the double throw switch' D. The circuitsin the modified form can be readily traced to both motors from the starting switch ,and through the The operation of the pneumatic control illus'-v trated in Fig. 7 is substantially the same a that of the preferred form.

In theoperation of either form, when the pressure in the tank C lowers sufliciently Yto permit the pressure switch A to close the circuit through the switch element 17 thereof, one of the pump motors 7 or 8 is started, de-

pending upon which circuit' happens to beu closed by the double vthrow switch.v The pump driven by said motor thereupon continues to, operate and build up the pressure in the vpressure tank until the ,pressure switch A is actuatedv to break .the circuit through the switch 17, whereupon the active motor stops.

When the pressure in the tank falls to a predetermined point, the diaphragm device Eis actuated by a spring in a direction to*` move' the switch o eratingx member F in a downwardly directlon, thereby throwing the movable contact membersl of the double throw switch over and closing the circuit throughsaid double throw switch to the motor ofthe other pump unit, and when the pressure'in the vtank falls to the predetermined low pointl for, closing the circuit v f through the switch 17 of the pressure switch u A, then the last mentioned pump motor is started and continues to v.run until pressure is built up in the pressure tank to the point required to actuate the pressure switch A' and break the circuit through he switch yelement 17 thereof. lln this manner, the motors are-I` started alternately and the active motor continues to operate until the necessary pressure isbuiltupu lln the event that the pressure inthe pressure tank falls below that required to start an idle pump so that the working pump is unable to build up the pressure, then the pressure switchl-A is operated-to close the circuit through the switch element'19 thereof, whereupon the idle pump unit is started as an 'auxiliary to theotheriactive pump'. The circuit through the pump which isv acting as an auxiliary is broken as soon as the` pressure in the tank is increased 'suciently to actuate the pressure switch B and break the circuit through its switch` 19. l

rlWhile the invention` has been shown and described as applied to a pressure system y wherein compressed air is employed,l it may be used in a vacuum system with equalfacil-ity and only such slight changes inthe pressure devices A, B and E are required as will adapt them to vacuum in'place of plus' pressure.

' lt is to be understood that the pumps of the pumping units maybe in the torni of water pumps for pumping liquids into or outof the tank C, andv that the pipes which connect the diaphragm devices withy the tank or other receptacle may open into the same above or istA below the water level therein. Furthermore,-

that while the switch operating devices A, B and E are illustrated in the form of diaphragm devices, other types of switch actuating devices responsive to variations or changes of the conditions in the tank or other receptacle C may be substituted for the diaphragm devices. Furthermore, that although the switch mechanism for controlling the two circuits for the two motors has been shown and described as a double throw switch, other equivalent switch mechanism may be employed whereby the circuits to the two motors may be'alternately closed and opened.

I claim as new, and desire to secure by Letters Patent:

1. The combination of two electric pump units opening to the same source and capable of operating in a regular sequence, a single pressure operated starting and stopping switch for both motors of said units, and automatic sequence control means associated with said starting and stopping switch and having an element whereby first one motor is started while another is quiescent and whereby said other motor is started while the iirst mentioned one is quiescent.

2. The combination of a tank, two electric pump units, each having a pump opening to said tank, a single pressure operated electric switch mechanism for closing the circuits to both electric motors of said pump units, said electric switch mechanism being responsive to Variations of pressure in the tank, and automatic sequence control means for the circuits to the motors of said pump units whereby the pump units are started in alternate sequence.

3. The combination of two electric motor operated pump units connected to a tank, and automatic pressure operated electric switch mechanism including sequence controlling mechanism for the motors of said pump units operating to start said motors alternately, said mechanism being responsive to Varia- A,tions of pressure in the tank.

4. The combination of two automatically controlled electric motor pump units connected to a tank yand capable of operating in,

'a regular sequence, a single electric pressure operated switch starting and stopping mechanis-In therefor responsive to variations of pressure in the tankand automatic sequence control means associated with said starting and stopping switch mechanism' and having an element whereby first the motor of one unit is started while the motor of the other is quiescent and whereby the motor of the other unit is started when the first one'is quiescent. l

5. The combination of a tank, two electric pump units, each having a pump opening to said tank, electric switch mechanism for closing the circuits to the electric motor of said pump units, said electric switch mechanism being responsive to variations of pressure in ity of motors comprising a pneumatically operated electric switch for starting and stopping the motors, and a pneumatically operated sequence controlling switch mechanism for establishing electrical connections between said switch and the motors in sequence, the pneumatic element of said switch and switch mechanism being connected to a pneumatic system and responsive to variations of pressure therein.

7. Means for controlling the sequence of operation 'of a plurality of electric motors comprising two electric circuits including an electric motor associated with each circuit, a pressure operated sequence controlling switch mechanism for the two circuits, responsive to variations of fluid pressure in a system, and other separately operating circuit controlling switch mechanisms, one for each circuit, and responsive to changes of conditions in said system.

8. Means for controlling the sequence of operation of a plurality of pump motors comprising an automatically operatin electric switch for starting and stopping tige motors, said switch being responsive to `changes of conditions in a fluid pumping systeln, and a pneumatically operated sequence controlling switch mechanism for establishing electrical connections between said switch and the motors in sequence, the pneumatic element of said sequence controlling mechanism being responsive to variations of pressure in said pumping system.

9. Control means for aplurality of motors Y comprising two electric circuits including an electric motor in each circuit, a fluid pressure operated sequence controlling switch mechanism for both motors, and a circuit controlling pressure lswitch for both motors, the pressure operated element of said sequence controlling switch mechanism and pressure switch being 'connected to a fluid pressure system and responsive to variations of pressure therein.

l0. Control means for a plurality of motors comprising two electric circuits including an electric motor in each circuit, a fluid pressure operated double throw sequence controlling switch for the motors, and a circuit controlling pressure switch for both motors, the vpressure operated elements for operating said double throw switch and said pressure switch being connected to a fluid pressure system and responsive to variations of pressure therein.

11. Control means for a plurality of mo- Ations ofpressure.

controlling mechanism,

tors comprising two electric circuits including an electric motor in each circuit, a fluid pressure operated sequence controlling switch mechanism for the motors, and two. circuit controlling pressure switches for the motors,

the fluid pressure operated elements of saidv sequence controlling switch and said pressure switches being connected to a fluid pressure system and responsive to variations of pressure therein, one pressure ,switch'being operable at a different' pressure than the other pressure switch, whereby one or both motors may be started in ,response to varia- 12. Control means for a plurality of motors comprising two electric circuits including an electric motor -in each circuit, sequence controlling switch mechanism for the motors,

and a circuit controlling pressure switch for` both motors connected to a iluid'pressure sys-v tem andresponsive to variations of pressure therein, in combination with .a Huid pressure operated switch thrwin device for said sequence controlling switc the pressure operated element of said switch throwing device being connected to a fluid pressure system and responsive to variations of pressure therein.

l13. Control means for a plurality of Amo- 'tors comprising two electric circuits including an electr-1c motor In each clrcult, a double throw sequence controlling switch for the motors, and a circuit controlling pressure switch for bothmotors and connected toa l fluid pressure system and responsive to `variations of pressure therein, i-n combination with a fluid pressure operated switch throwing device for said double throw switch, the ressure operatedv element of saidswitch throwl ing device being connected to said duid pressure system and operated at a higher pressure than that required vto actuate said pressure switch.

' l 1d. Control means lor a plurality ol motors comprising electric switch sequence controlling mechanism for the electric circuits ot two motors, a duid pressure operated switch connected to a tluidpressure system and inter in the circuit through said sequence and duid pressure operated means for actuati said sequence controlling mechanism.,J

'15. Control means lor a plurality of motors comprising. electric switch sequence controlling mechanism lor the electric circuits to two motors, a duid pressure operated switch connected to a duid pressure system and interposed in the circuit through said vsequence controlli mechanis, and

vHuid*-.pressure operated switch throwing means connected to said lduid pressure sys-.; tem -and actuating said sequence controlling"` mechanism.

V16. Control means tors comprising a double t row switch for lluid pressure actuated switch thro uw for al lurality ol mo-y controlling circuits to two motors, a swltch connected to a fluid pressure s stem P and interposed in the circuit throng :the

double throw switch, and switch throwing means connected to said fluid pressure system 70 and voperating the double throwing'switch.

17. `Control means for a plurality of mo- -tors'comprisinga double throw lswitch for controllmg electric circuits to two motors, a pressure switch connected to a fluid pressurem system and interposed in the circuit through ,the double throw switch, a pressure actuated device connected to said fluid v tem, and switch throwing mec anism connected to` and operated bysaid pressure ac- 80' ressuresystuated device. 18. Control means for a plurality ofvmotors comprising electric switch mechanism for controllingelectric circuits'to. two motors, a pressure operated' electric switch con- 85 nectedto a' Huid pressure system and inter posed in the circuit through said electric switch mechanism, said pressure operated electric switch acting to close the circuit through said electric switch mechanism when '1 the pressure in the system falls-to a predeterressure operated' v mined low point, and means lor actuating said electric switch mechanlsm, said last mentioned pressure op-1 erated means beingset to operate 'at a higher ou pressure than the pressure'operated electric Y switch, whereby the electric switch mechal. nism is actuatedv when the circuit .therethrough is broken. i

19. Control'means tors comprising electric switch mechanism Vfor controlling electric circuitslto 'two motors, duid pressure operated means for actu-4 ating sald electric switch mechanism and .connected to a duid pressure' system,a` Huid litt means connected to a duid pressure system andacting to throw said switch 'while the pressure in thesystem is falling, and apressure switch connected to said duid systemand interposed in the circuit through f the douhlethrow switch.

2l. ln automatic control mechanism t'orI pump apparatuathe 'combination oi al l tank, a pair ot duid pressureoperatedand electrically controlled alternately lacting mofor a plurality of motto tor driven pumps connected to said tank,

' and fluid pressure operated control means for vmotors comprising fluid pressure operated electric switches for starting and stopping l both motors, the one switch being set to opcrate at a different pressure than the others and there being one switch for each motor, and fluid pressure operated sequence control switch mechanism for establishing electrical connection between said switches and the motors, the pressure operated element for said switch and switch mechanism being connect- AUGUSTUS C. DURDIN, JR. u

ed to a fluid pressure system and responsivefto variations of pressure therein.

24. Control means for a plurality of motors comprising a plurality of electric circuits including an electric motor for each circuit, a fluid pressure operated sequence controlling switch mechanism for the motors, and a plurality of fluid pressure circuit controlling switches for the motors co-operating with the sequence controlling switch mechanism to cause operation of said motors in sequence and in unison, the pressure operated element of said electric switch mechanism being connected to a fluid pressure system and responsive to variations of pressure therein.

25. Means for controlling the sequence of operation of a plurality of electric pump motors comprising two electric circuits including an electric motor associated with each circuit, and Huid pressure operated sequence controlling switch mechanism for `the two circuits, the fluid pressure operated element of said switch controlling mechanism being responsive to variations of fluid pressure in a system, and separately operating other circuit controlling mechanism, one for each electric circuit and responsive to changes of conditions in said system.

26. Control means fora plurality of motors comprising a fluid pressure operated electric switch for starting and stopping the motors, sequence control switch mechanism for establishing electrical connection between said switch and the motors, in sequence, a

' second fluid pressure operated electric switch for starting and stopping the motors, the pressure operated element of said electric lio 

